Does success make us happy or does happiness make us successful?

These best and brightest willingly sacrificed happiness for success because, like so many of us, they had been taught that if you work hard you will be successful—and only then, once you are successful, will you be happy. They had been taught that happiness is the reward you get only when you become partner of an investment firm, win the Nobel Prize, or get elected to Congress.

But in fact, as you will learn throughout this book, new research in psychology and neuroscience shows that it works the other way around: We become more successful when we are happier and more positive. For example, doctors put in a positive mood before making a diagnosis show almost three times more intelligence and creativity than doctors in a neutral state, and they make accurate diagnoses 19 percent faster. Optimistic salespeople outsell their pessimistic counterparts by 56 percent. Students primed to feel happy before taking math achievement tests far outperform their neutral peers. It turns out that our brains are literally hardwired to perform at their best not when they are negative or even neutral, but when they are positive.